The present application claims benefits of Japanese Applications No. 2002-358297 in Japan on Dec. 10, 2002, No. 2002-358298 filed in Japan on Dec. 10, 2002, No. 2003-402273 filed in Japan on Dec. 1, 2003, No. 2003-402274 filed in Japan on Dec. 1, 2003, the contents of which are incorporated by this reference.
1. Field of the Invention
This invention relates to a camera having a distance measuring apparatus and more particularly, it relates to a camera having a distance measuring apparatus having a multi-autofocus function with which ranges of a plurality of areas in a photographing plane are found.
2. Related Art Statement
As is widely known, there are two autofocus (hereinafter, called AF) types used for the distance measuring of a camera: one is a xe2x80x9cpassive typexe2x80x9d in which an AF sensor disposed in the main body of a camera directly receives an image signal (optical image), the other is an xe2x80x9cactive typexe2x80x9d in which a camera projects distance measuring fill light toward an object and receives its reflected light.
Also, even in a passive AF camera, when an object lies in a dark-place or the contrast of an object is low, fill light is projected for lighting up the object or for making the variations of brightness and darkness larger on the object, so that a process of an active type is performed so as to improve distance measuring accuracy.
In addition, a technique with which a fixed-light removing function for removing a component of light reflected at an object other than the fill light or distance measuring light (hereinafter, the component is called fixed light) is provided so as to improve detecting accuracy of the reflected light has been also known and disclosed in Japanese Unexamined Patent Application Publication No. 5-40037.
Briefly speaking, a camera having a distance measuring apparatus which performs distance measuring of a plurality of distance measuring areas in a photographing plane, according to the present invention, includes a photo-receiving lens, each forming an object image; a photo receiving unit receiving the object image formed by the photo-receiving lens; a computing unit computing data about object-to-camera distances on the plurality of distance measuring areas on the basis of outputs of the photo receiving unit; a selecting unit selecting any one of the distance measuring areas in the photographing plane on the basis of the computed results of the computing unit; and a determining unit determining whether or not an extreme value exists in outputs of the photo receiving unit, in the distance measuring area selected by the selecting unit, and when the determining unit determines that the extreme value does not exist, the selecting unit selects a second distance measuring area different from the initially-selected first distance measuring area.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.